By Jack Rosebro
|A Prius in crash-testing.|
As the world’s fossil fuel supply tightens, an increasing number of innovative vehicles are appearing on our roads.
With conventionally-fueled vehicles increasingly supplanted by alternative-fueled transportation such as electric neighborhood vehicles, compressed natural gas vehicles, gas-electric hybrids, and a smattering of hydrogen fuel-cell prototypes, the life of the emergency responder—particularly the firefighter called upon to extricate accident victims from the wreckage of their cars—has become correspondingly more complex.
Information and potentially life-threatening misinformation regarding hybrids in particular have appeared in the media with increasing regularity; one dealership salesman was quoted in an article, for example, as assuring customers that hybrids have:
...a bright orange cord...to let emergency personnel know where the high-voltage wires run, so in case of an accident, they can snip that. Turns all the electrical voltage off.
It should be noted that no hybrid manufacturer advocates the cutting of high-voltage, high-current cables under any circumstance.
Existing technology had already been complicating the life of the firefighter well before hybrids became commercialized. Hidden airbags can inflate without warning as a vehicle is being cut apart. Pressurized by the heat of a vehicle fire, a component as innocuous as a hood strut cylinder can become a missile that pierces a responder’s thigh. Such concerns now require consideration at the design level.
|Ron Shaw, of Extrication.com|
With this in mind, Green Car Congress recently sat down with extrication instructor Ron Shaw to discuss the rapidly increasing technology present in today’s vehicles, and in innovative vehicles in particular. The interview also touched on the challenges presented by hydrogen fuel-cell vehicles.
Mr. Shaw is lead instructor and owner of Extrication.com, a Massachusetts-based organization dedicated to teaching firefighters and other first responders across North America how to evaluate safely and quickly the scene of a vehicle accident and to extricate victims. He has also worked with Toyota and Lexus on Emergency Response Guides (ERGs)—provided free of charge to first responders—for those hybrids.
GCC: How do you recommend that firefighters and other first responders deal with the high-voltage circuits present in hybrids, when extricating accident victims from these vehicles?
RS: One of the most important recommendations I can offer responders is to learn about innovative vehicles today for the crash of tomorrow. The only way to do this is through proper education by responsible educators who are knowledgeable in hybrid or other innovative technology. If I had to limit my answer to the single most important task, it would be to tell the responder to turn the vehicle’s ignition/power switch/button to the OFF position/mode.
GCC: At Green Car Congress, we come across quite a few myths and misinformation about the technical aspects of hybrids and other vehicles. Some of these myths are promoted by sources that can appear reliable to the uninformed. Do you see the same thing in your profession?
RS: Since the introduction of hybrid vehicles, responders have increasingly expressed their concern for the higher voltage in vehicles. However, much of the concern is unwarranted and propagated by misinformed responders and/or by irresponsible reporting by the media who fail to validate their reporting from a reliable source. Can injuries or death occur from a high voltage vehicle? Yes, but they also can occur with innovations in a conventional vehicle, including higher voltage currents.
GCC: In a very general sense, what does it take to stabilize a hybrid at a crash scene?
RS: There are several tasks that responders need to follow at any crash, including innovative vehicles:
Immobilize the vehicle (chock or block the wheels and turn the vehicle off);
Stabilize (crib to the frame at four points); and
Disable (perform low voltage power disconnect).
When extrication is required, one of the simplest ways to provide a safer environment is to turn the vehicle OFF and remove the key or smart keyless FOB away from vehicle. In the past responders were told to leave the keys on the dash. With the introduction of the smart keyless system this has been updated to remove the key/keyless FOB to as much as 15 feet from the vehicle.
Shutting the vehicle OFF will accomplish the following safety issues:
Shuts down the hybrid system;
Isolates the high voltage current;
Stops (low voltage) power to the SRS electric control unit (ECU); and
Shuts down the internal combustion engine and fuel pump.
Another hybrid concern responders have is being electrocuted by simply touching the body of a crash vehicle having a high voltage current. This is a misconception. Electric, hybrid and fuel cell vehicles do not use high voltage as a body chassis ground. Touching the body of a vehicle, even if submersed will not in itself cause electrocution. A responder would have to touch pole to pole or become part of the circuit for an injury to occur. Responders should not have a need to cut a high voltage power cable, which is normally identified by the SAE standard color-coding of bright orange.
GCC: The new Mercedes-Benz S-class reportedly has identifying marks showing the hidden location of airbag inflators located underneath its interior trim. How important is this to your profession?
RS: Like Toyota and other companies, Mercedes-Benz is approaching vehicle extrication issues proactively. However, showing where to safely make cuts into a pillar only addresses breaching the inflator. I feel that undeployed airbags should not be cut, or cut only as a last resort, and only when absolutely necessary. Showing “Cut Here” implies that it is safe to cut into an undeployed airbag. If there is an accidental deployment of the SRS you now have an opening for hot gases to come out. Any cut glass fragments or metal can now become projectiles and enter unprotected soft tissues such as the eyes. Perhaps using an identifier denoting “airbag inflator” would be more beneficial.
Personally, I would rather have the gases restrained by the airbag (curtain) than have to cut into one. For the most part, a vehicle’s roof does not have to be displaced or removed, even when performing a dash displacement [editor’s note: a dash displacement is a technique that rolls a vehicle’s dashboard assembly up and away from a trapped victim or victims so as to free them]. There are alternatives to roof displacement such as cutting along the side of the roof rails and removing the center section out if the curtains have not been deployed.
Responders have to react to the situation on-hand and sometimes think out of the box instead of “this is the way we have always done it!” Vehicles are not the same as they were twenty, ten or five years ago. We have to prepare for today’s crash with innovative vehicles using innovative thinking.
GCC: What can those who design vehicles do to make things easier and safer for first responders, as well as the accident victims they are called upon to rescue?
RS: There are important suggestions that I feel would be more beneficial to emergency responders such as:
Install an emergency power disconnect switch that would completely power down the vehicle (low and high voltage systems);
Have SRS components mounted in specific mounting sites; and
Make available a model’s emergency response guides (ERG) prior to the introduction of the vehicle to enable responders to learn about the vehicle prior to its sale.
GCC: The introduction of alternative-fueled and alternative-technology vehicles has given rise to emergency response guides (ERGs) for these vehicles. What do you feel an ERG should look like and/or contain?
RS: Emergency response guides should be generic in format. Today, every automaker has their own ERG format, and many lack all the information responders need at an incident to safely mitigate a rescue.
GCC: How can risks to the responder be reduced at the vehicle accident scene?
RS: Emergency services are risk-based. Like conventionally-fueled vehicles, alternative-fueled vehicles also have risks. Responders have to learn what to do, and what not to do. This can only be done through proper education. Education replaces fear. Never has so much information been available to emergency responders about vehicle systems by manufacturers as a whole. The problem we now face is getting this information to the end user before they need to use it.
GCC: Although much has been made of safety concerns regarding hydrogen, the industry, and in particular the California Fuel Cell Partnership, have been proactive in getting some dialogue going with first responders (earlier post). However, the industry also seems to be leaning toward a 10,000 psi (700 bar) fuel-storage standard. If such technology becomes commonplace, what concerns do you have for first responders as they approach incidents involving hydrogen fueling stations and vehicles?
RS: Hydrogen has gotten a bad rap from the Hindenburg incident, which was not caused by a hydrogen leak as once thought. It was proven at the time by the Hindenburg’s owners to have been caused by electrostatic discharge as the airship passed through a highly electrified air mass. The conductive doping built up a strong electrical charge and it is believed that due to poor bonding to the structural frame work an arc between the skin and the frame started the fire.
Reviewing still photos and newsreel footage, it appears the fire started in the aft section of the airship and burned downward. Hydrogen burns upward. Once the fire reached the hydrogen storage bladders (made of animal tissue coated with gelatin) the domino-like chain reaction engulfed the vessel.
Most of the passengers survived, and most of those who died were killed when they jumped. The US had similar problems with airships filled with helium, a non-flammable gas, and changed the protective doping with no further problems.
GCC: From a safety standpoint, how does a hydrogen-based vehicle’s fuel and storage system differ from the gas and diesel-powered vehicles in use today?
RS: Hydrogen is a safer automotive fuel than hydrocarbons fuels such as gasoline. The advantage is that it will quickly dissipate into the atmosphere due to its molecular weight. Gasoline and diesel fuel are heavy, and has a tendency to pool at the ground level creating a flammable environment at the scene of a crash.
It has been estimated that should there be a leak from high pressure fuel tanks it would take approximately three minutes to empty all the tanks. However, with the use of internal valves the threat of leakage is minimal. The tanks are extremely strong and similar in design to those used for compressed natural gas (CNG).
Should a fire develop, hydrogen has very little radiant heat and would contribute little to the rise of the ambient cabin temperature (approximately 2-3 degrees F). I would much rather go to a hydrogen-fueled vehicle fire than a fossil-fueled vehicle fire.
There are also hydrogen leakage safety systems in place in hydrogen fueled vehicles. Should a sensor detect a measurable leak, the vehicle fuel supply will immediately shut down. Hydrogen internal combustion engine and fuel-cell powered prototype vehicles have been in use for years and as far as I know, there have been no reportable incidents caused by hydrogen.
Refueling stations are very safe; the operators are given extensive training in fueling and safety procedures. Most likely, there will be an electronic sensing system that will communicate between the vehicle and the refueling unit to ensure that all safety features are in place prior to the discharge of hydrogen from the refueling unit to the vehicle's intake.
GCC: How do firefighters approach hydrogen fires?
RS: Hydrogen fires are handled in a similar manner as other flammable gases are handled. The only difference would be that hydrogen has an almost colorless flame, however a high pressure leak would surely be recognized from the high pitched shrill noise of venting gases.
Again, a high pressure hydrogen leak in a vehicle is not likely, due to the tank’s internal safety features, as well as external safety features such as pressure-relief devices. Thermal imaging cameras are used, as is the less modern, but very effective corn broom for fire detection which is used to detect fires with invisible flames. I recently spoke to a nuclear power plant safety officer who trains with hydrogen fires, and the corn broom is still their method for fire detection.
GCC: Are reliable technical resources available to responders regarding hydrogen today?
Both have websites and are in the process of releasing training programs that can be utilized by the emergency services. We are still about a decade away from the sale of consumer fuel-cell vehicles and refueling stations, but I am confident that the training will be well in place by that time. I would estimate that the fire service will have training programs available within the next two to three years based on recent roundtable meetings.
Hybrid vehicles were introduced well before information was readily available to the emergency services. The industry has now seen this to be detrimental, and is actively preparing to train emergency services well before its introduction of consumer available hydrogen fueled vehicles. I am confident the emergency services will be able to properly and safely handle any incident involving hydrogen fueled vehicles in the future.
Toyota and Lexus Hybrid Emergency Response Guides (Click on “Emergency Response and Hybrid Vehicles”)